Self-energizing breech seal for guns



Oct. 31, 1961 R. J. THIERRY SELF-ENERGIZING BREECH SEAL FOR suns Filed Feb. 17, 1960 :E' El- INVENTOR. RUhEI1J ThiE T U 3,006,254 SELF-ENERGIZING BREECH SEAL FOR GUNS Robert J. Thierry, Averill Park, N.Y., assignor to the United States of America as represented by the Secretary of the Army Patented Oct. 31., 1961 It is a further object of this invention to provide a ring seal wherein the sealing surfaces thereof contact the seats therefor as close to an an angle of 90 as possible to prevent both a wedging effect between the separating members and a stretching of the sealing surfaces of the seal .Jnilni. t tan 1 /e-'! minim Fil a F b.17' 1960 serffioififii" i M1 s e 4 2 m 39 25 It is still another ob ect of this invention to form the (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to closure seals for high pressure vessels and particularly to such seals which are adapted to obturate the breech closures of guns and are energized by gas pressures therein.

In large caliber guns wherein the propellant and projectile of a round are handloaded separately into the gun and where space rearward of the breech for such handloading is critical, it has been found advisable to have the chamber mounted for separation from the firing tube so that the propellant can be loaded rear-wardly into the chamber and the projectile inserted forwardly into the tube. In mortars, it has also been found advantageous to have the launching tubes separable to facilitate loadmg.

With such gun structures, it is, of course, necessary to obturate the joint between the separable members. This requires a seal which must be carried by one of the separable members and which must make sealing connection therebetween each firing cycle. Consequently, the seal must be designed so that it can be used frequently and for a large number of cycles. It must also be extendable relative to the longitudinal axis of the tube so as to maintain sealing connection with the separating members if the joint therebetween is dilated by discharge forces.

The mechanical load which can be applied to the seal in such gun applications is not suflicient to effect complete sealing of the joint between the separating members because of the limited axial force which can be applied therebetween when swung to the closed position. Consequently, it is necessary for the seal to be energized by the gas pressure produced when the propellant is discharged in the chamber.

The available self-energizing seals for high pressure vessels which might be adaptable to such gun structures are modifications of the Bridgman, delta, lens, wave and 0 types. These seals, however, are not satisfactory for gun use because they use the unsupported area principle and, therefore, produce a gradual and progressive yielding which increases the dimensions of the seal to the extent that the chamber is prevented from closing after only a few rounds.

It is, therefore, the principal object of this invention to provide for high pressure vessels, such as guns, a closure seal which is self-energized and which functions without being deformed beyond plastic limits so that sealing connections can be made frequently and a large number of times without a material change in the dimensions of the seal.

It is a more specific object of this invention to provide such a seal which conforms to the seats provided therefor in the separating members so that the sealing surfaces of the seal are fully supported and nearly all of the load applied against the sealing surfaces is transferred directly to the structures of the separating members.

It is another object of the invention to provide a ring seal wherein the initial contact portions of the sealing surfaces are increased as the seal is loaded to relieve the contact pressure of the sealing surfaces as the pressure applied thereagainst builds up.

seats for such a ring seal so as to also provide a restricted area adjacent the inside areas of each of the sealing surfaces to produce a throttling effect to assist in establishing the initial seal and to delay the action of the gas pressure on the sealing areas.

It is a still further object of this invention to provide a labyrinth effect in the seal geometry so that the pressure of the escaped gases will be reduced to safe limits before reaching the atmosphere in event of seal failure.

It is another and still further object of this invention to provide a ring seal which is adapted to scrape clean the receiving seats when making sealing connection and provide a receiving pocket for the scrapings in the geometry of the seat.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is an enlarged and fragmentary cross-sectional view showing the ring seal assembled to a gun tube to obturate the joint between the tube and a separable breech member which is shown adjacent the closed position thereof relative to the tube with a zero mechanical preload applied to the ring seal;

FIG. 2 is a view similar to FIG. 1 but showing the breech member in the closed position and the ring seal mechanically preloaded; and

FIG. 3 is a view taken along line 3-3 of FIG. 1.

Shown in the figures is a gun structure including a tube 12, a breech member 14 separable therefrom, and a ring seal 16 which is carried by the tube for obturating a joint 1-8 formed between the breech member and tube when the breech member is in the closed position respective thereto. Tube 12 includes a bore 20 and breech member 14 is provided with a chamber 22 which has the same diameter as such bore and is coaxial therewith when the breech member is in the closed position. Breech member 14 is swung to and from the closed position by a mounting device (not shown) which imparts limited axial movement to the breech member during final movement to the closed position and initial movement therefrom. Whereby, breech member 14 is spaced clear of seal 16 when moving transversal to tube 12 and the seal is mechanically preloaded during final portions of the axial movement of the breech member to the closed position.

Seal 16 includes a central section 24 having a flat backing surface 26 therearound. A pair of flangelike sealing sections 28 extend integrally from opposite sides of central section 24 so as to be disposed parallel to the axis of seal 16. Each of the sealing sections 28 includes a fiat sealing surface 30 which extends around the outside thereof parallel to the longitudinal axis of seal 16. The sealing surfaces 30 are extended to join the adjacent edges of backing surface 26 by' a pair of concave surfaces 32 which are blended into the sealing surfaces. The sealing surfaces 30 and the blend portions of concave surfaces 32 adjacent thereto are polished to a smooth finish and the sealing surfaces have a greater length than any possible dilation of joint 18.

-The sealing sections 28 have a uniform thickness and the inside surface of central section 24 is contoured to form with concave surfaces 32, where blended into the sealing surfaces 30, a pair of arcnate sections 34 having the same thickness as the sealing sections 28. V Vhereby, the sealing sections 28 may be flexed respective to central section 24, without distorting sealing surfaces 30. As has been stated hereinbefore, seal 16 is carried by tube 12. 'Provided in tube 12 at the juncton of bore 20 "and the rear face thereof is a seat '38 which receives central portion 24 and one of the sealing sections 28 of seal 16. Seal'16 is retained in seat 38 by a pair of diametrically disposed tabs 40 which are secured as'by a screw 41 within mating-recesses provided therefor in the rear face of tube 12. Tabs 40 include lip portions 42 which are contactable by the concave surfaces 32 on the outside of seal 16 and such lip portions are disposed to permit sufficient movement of the seal within seat 38 to perform the sealing functions as hereinafter described.

'When breech member 14 is in'the closed position, the

opposite one of the sealing sections 28 is received by a seat 44 formed in the breech member at the junction of the rear face thereof with chamber 22.

at C is .0015. Because of this difference in radii and the fiexure of the sealing surfaces 30, the axial pressure of breech member 14 is concentrated at points 0 to mechanicaliy preload seal 16. pressure are created in chamber 22 and bore 20, the gases which pass through orifices 56 produce a throttli-ng effect. which serves tolbend the sealing sections 28 for full and firm contact between the sealing surfaces 30 and 52 with theincreased pressure between the sealing surfaces being proportionate to the gas pressure, As the sealing sections 28 are bent, the area ofcontact of seal 16 with the seats38 and 44 is increased to relieve the stresses in the seal. I

The throttling effect of the orifices 56 and the dispositionof the pockets 54 between the orifices 56 and sealing surfaces 30 and 52 delays the impact of the gases sequently, central section 24. Seat 38 "also includes a convex surface 48 which extends 'therearound to coincide' with concave surfaces 32. However, the radiusof convex surface 48 is slightly less than that of concave f surfaces 32. In the present embodiment, wherein the diameter of seal 16 is 6", the radius of the'convex surface is .l" while that of the concave surfaces 32 is .140. This provides a point 0, located along the out side surface of'arcuate section 34, at which the concave surface 32 and convex surface 42 make initial contact when breech member 12, is adjacent'the closed position.

. It'is desirable that convex surface 48 be formed so that the angle of contact between concave surface 32 and convex surface 42 at point 0 be as close to 90 as possible. Thus, when pressure is applied to seal 16, the

' pressure is transferred in as near a straight line as possible to convex surface 48 to eliminate any Wedging action which would tend to increase the dilation of joint 18 or stretch and tear sealing section 28. The total dilation of the seal will thereby be limited by the composite structure of the seal and the surrounding outer members of the breech closure cylinders.

Seat 38 is provided with a recess 50 which extends into tube 12 longitudinally respective to the axis thereof and which is arranged to receive the related one of the sealing sections 28. Recess 50 includes a sealing surface 52 which is disposed parallel to the axis of the bore so as to be contactable by sealing surface of seal 16 and provide full support for the corresponding one of the sealing sections 28. Recess 50 extends beyond the outside edge of sealing section 28 to form a pocket 54 therebeyond and is slightly wider than the sealing section to form an orifice 56 with the inside surface of the sealing section. Sealing surface 52 is blended into the adjacent convex surface 48 and is provided with a polished finish so as to make as complete a contact with sealing surface 30 of seal 16 as possible.

The configuration of seat 44 in breech member 14 is reversely similar to that portion of seat 38 which cooperates With the related one of the sealing sections 28 and, therefore, the elements of seat 44 are given the same reference numbers as those indicated for seat 38 for clarity of description.

Because of the differences in the radii of the convex surfaces 48 and the concave surfaces 32 and the location of the points 0 along the arcuate sections 34, the axial movement thereof, when breech member 14 is brought to the closed position, causes the sealing sections 28 to be flexed at the arcuate sections so as to provide a slight clearance between the sealing surfaces 30 and 52 at the outer ends of the sealing sections 28. The flexure of the sealing sections 28 should not be great enough to distort the sealing sections beyond the elastic limits thereof. In the present embodiment of the clearance noted The concave surfaces 32 of seal '16 make initial contact'with the convex surfaces of seats 33 and 44 at points 0 and then, during final axial movement of the breech member, the seal is mechanically preloaded with the sealing sections 28 bent to form the clearances When the gun is discharged, the resulting gases upon reaching the vicinity of joint 18 pass through the orifices 56 to create athrottling' effect thereat which bends the sealing sections 28 for full sealing contact between the sealing surfaces 38 and 52. With the bending of the sealing sections 28, the stresses in sealingsections 28 are relieved through the increasedarea of contact thereof with the seats 38 and 44. The pockets 54 provide a time delay to enable full sealing contact between the sealing surfaces 31 and 52 before the full impact of the gases impinge on the joint therebetween.

From the foregoing it is clearly apparent that there is provided herein a seal which is especially well suited for sealing the closures of high-pressure vessels, such as guns, wherein the sealing connection has to be made frequently and a large number of times, as the seal is entirely supported by the structure of the vessel to prevent yielding. Furthermore, all fiexures of the sealing sections are kept within plastic limits and the pressure of the seal is applied substantially direct to the supporting structures to prevent any wedging or stretching action.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within tthe spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In a gun having two separable members respectively provided with a bore extending thereinto from an end thereof for receiving high pressure gasses generated therein from the discharge of ammunition, said members being adapted for actuation to a closed relationship wherein the bores of similar diameter are coaxially aligned and the ends of the members are in abutment, a seal system for preventing the escape of the gases between the ends of the members when in closed relationship, said seal system including a ring seal energizable by the pressure of the gases in the bores, said ring seal being provided with a pair of sealing sections extending oppositely from a central section parallel to the longitudinal axis of said ring seal, a first seat formed in one of the members for receiving said central section of said ring seal and one of said sealing sections, means for retaining said ring seal in said first seat, a second seat When gases of greater formed in the other one of the members for receiving the other one of said sealing sections when the members are in closed relationship, said first and second seats being formed so as to be open to the bores when the members are in closed relationship to permit action of the gases in the bores against the inside surfaces of said sealing sections, a sealing surface provided around the outside of each of said sealing sections, a sealing surface provided in each of said first and second seats so as to have contact with the associated ones of said sealing surfaces in said sealing sections when the members are in closed relationship, an annular pocket formed in each of said first and second seats, an orifice formed between each of said first and second seats and the inside surface of the associated one of said sealing sections at the mouth of the associated one of said pockets for concentrating the pressure of the gases from the bores against said sealing sections when passing from the bores to said pockets and for delaying the impingement of the gases from the bores against the area of contact between said sealing surfaces on said sealing sections and said first and second seats, and structure formed in said first and second seats so as to coincide with the geometry of said ring seal for supporting said ring seal to prevent a yielding thereof by gas pressure when applied thereagainst.

2. The seal system as defined in claim 1 wherein said sealing surfaces on said sealing sections and on said first and second seats are disposed parallel to the axis of the bores and said sealing sections are disposed so as to scrape clean said sealing surfaces in said first and second seats when the separable members are actuated to the closed position, and wherein said pockets are disposed to collect the debris cleaned from said sealing surfaces of said first and second seats.

3. The seal system as defined in claim 1 wherein said sealing sections are joined to said central section by arcuate sections of the same thickness as said sealing sections whereby said sealing sections may be flexed by the gas pressure Within the boxes without a distortion of said sealing surfaces on said sealing sections.

4. The seal system as defined in claim 1 wherein said sealing sections are joined to said central section by arcuate sections of the same thickness as said sealing sections and the structure of said first and second seats supporting said arcuate sections has a shorter radius than that of said arcuate sections to provide a point of initial contact between said seal and said first and second seats when the separable members are adjacent the closed position and flex said sealing sections outwardly at said arcuate sections within the plastic limits thereof for partially displacing said sealing surfaces on said ring seal from said sealing surfaces in said first and second seats when the members reach the closed position to mechanically preload said seal, and said orifices are disposed for concentrating the pressure of the gasses passing thereby against the ends of said sealing sections for flexing said sealing sections at said arcuate sections to increase the area of contact between said sealing sections and said first and second seats, and wherein said sealing sections are flexibly responsive to the pressure of the gases in the bores so that the total pressure of the gases and the mechanical preload is sufficient to prevent the escape of the gases past said seal.

References Cited in the file of this patent UNITED STATES PATENTS 1,376,130 Asbury Apr. 26, 1921 FOREIGN PATENTS 125,126 Great Britain Apr. 17, 1917 

